Processing apparatus

ABSTRACT

A processing apparatus includes a processing feed unit and a control unit. The processing feed unit moves a holding unit along guide rails between a processing zone, and an imaging zone in which a workpiece is imaged by a camera. The control unit includes a correction amount calculation section configured such that, after forming a cut groove in the workpiece, the cut groove is imaged by the camera, and correction values in a Y-axis direction or a correction angle for the chuck table are or is then calculated from Y-coordinates of two points apart from each other in a processing feed direction on the cut groove, whereby when carrying out processing feed of the chuck table in the imaging zone, the camera is corrected in position in the Y-direction based on the correction values or the chuck table is rotated by the correction angle.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a processing apparatus.

Description of the Related Art

There are known processing apparatuses for processing a workpiece suchas a device wafer along streets. The device wafer is formed fromsilicon, sapphire, gallium arsenide, silicon carbide (SiC) or the like,and carries a plurality of devices formed in regions defined by thestreets (see, for example, JP 2017-199777 A). The processing apparatusesof this type include cutting apparatuses, each of which cuts a workpiecealong streets by a cutting blade mounted on a spindle, and laserprocessing apparatuses, each of which focuses a laser beam to streets ona workpiece to form laser-processed grooves along the streets in theworkpiece or to form modified layers along the streets inside theworkpiece.

With each processing apparatus described above, a workpiece is held on achuck table, and is processed while it is moved along guide rails in aprocessing feed direction (an X-axis direction). If the streets of theworkpiece are directed parallel to the X-axis direction beforehand byrotating the chuck table, processing is possible along each street bymoving the chuck table in the X-axis direction.

SUMMARY OF THE INVENTION

In the above-described processing apparatus, the chuck table is moved bya linear actuator that includes a holding unit (moving base) movablealong guide rails. However, linear travel accuracy of the linearactuator is guaranteed for only a specified travel range (hereinaftercalled “the guaranteed range”) that excludes its opposite ends. In avicinity of the opposite ends of the guide rails, the linear travelaccuracy is therefore low compared with that in the guaranteed range, sothat the chuck table may slightly rotate as viewed in plan (as viewedfrom a camera) or may be fed for processing in the rotated state. If theworkpiece is subjected to an alignment (its processing position isdetermined) or to a kerf check (its cut position is measured or adjustedfor any positional deviation) in a region of any one of the oppositeends, processing may be performed at a wrong position, thereby possiblyleading to a reduction in processing accuracy. If the guaranteed rangeis widened to the opposite ends or the linear actuator is increased inlength to widen the guaranteed range, however, the linear actuatorrequires a higher cost and/or a larger installation space.

The present invention therefore has as an object thereof the provisionof a processing apparatus that can suppress a reduction in processingaccuracy while suppressing an increase in cost.

In accordance with a first aspect of the present invention, there isprovided a processing apparatus including a holding unit having arotatable chuck table configured to hold a workpiece, a processing unitconfigured to process the workpiece held on the chuck table, aprocessing feed unit that carries out processing feed of the holdingunit in an X-axis direction, an indexing feed unit that carries outindexing feed of the processing unit in a Y-axis direction, a camerathat images the workpiece held on the chuck table and is movable in anindexing feed direction, and a control unit configured to control theholding unit, the processing unit, the processing feed unit, theindexing feed unit, and the camera. The processing feed unit includesguide rails, and is configured to move the holding unit along the guiderails between a processing zone, in which the workpiece is processed bythe processing unit, and an imaging zone, in which the workpiece isimaged by the camera at a position that is apart from the processingzone by a predetermined distance in the X-axis direction. The controlunit includes a correction amount calculation section configured suchthat, after forming a linear processed mark in the workpiece by theprocessing unit while carrying out processing feed of the chuck table,the chuck table is moved to the imaging zone, the processed mark isimaged by the camera, and correction values in the Y-axis direction or acorrection angle for the chuck table are or is then calculated fromY-coordinates of two points that are apart from each other in aprocessing feed direction on the processed mark, whereby when carryingout processing feed of the chuck table in the imaging zone, the camerais corrected in position in the Y-axis direction based on the correctionvalues or the chuck table is rotated by the correction angle.

In the processing apparatus according to the first aspect of the presentinvention, the chuck table may preferably have a transparent member thatforms a holding surface configured to hold the workpiece thereon, thecamera may preferably have, at positions which are up and down with thetransparent member interposed therebetween, a first camera in a vicinityof the processing unit and a second camera that is more distant than thefirst camera from the processing unit, and the control unit maypreferably further include a coordinate storage section configured tostore in terms of X and Y-coordinates a positional deviation between thefirst camera positioned to image a predetermined region on the workpieceheld on the chuck table and the second camera positioned to image thepredetermined region, and may preferably be configured to correct theposition of the second camera based on the X and Y-coordinates stored inthe coordinate storage section such that the second camera can image thepredetermined region imaged by the first camera.

In the processing apparatus according to the first aspect of the presentinvention, the processing apparatus may preferably further include adisplay unit that displays a first image captured by the first cameraand a second image captured by the second camera. The control unit maypreferably further include an image control section configured todisplay the first image and the second image in superposition orjuxtaposition on the display unit with one of the first image and thesecond image being inverted in the processing feed direction.

In accordance with a second aspect of the present invention, there isprovided a processing apparatus including a holding unit having arotatable chuck table configured to hold a workpiece, a processing unitconfigured to process the workpiece held on the chuck table, aprocessing feed unit that carries out processing feed of the holdingunit in an X-axis direction, an indexing feed unit that carries outindexing feed of the processing unit in a Y-axis direction, a camerathat images the workpiece held on the chuck table and is movable in theY-axis direction, and a control unit configured to control the holdingunit, the processing unit, the processing feed unit, the indexing feedunit, and the camera. The processing feed unit includes guide rails, andis configured to move the holding unit along the guide rails between aprocessing zone, in which the workpiece is processed by the processingunit, and an imaging zone, in which the workpiece is imaged by thecamera at a position that is apart from the processing zone by apredetermined distance. The camera has a first camera in a vicinity ofthe processing unit, and a second camera that is more distant than thefirst camera from the processing unit. The control unit includes acorrection amount calculation section configured to image a linear markin the workpiece or the chuck table by the first camera, to rotate thechuck table to adjust the mark to a direction parallel to the X-axisdirection, to move the chuck table to the imaging zone to image the markby the second camera, and then to calculate correction values in theY-axis direction or a correction angle for the chuck table from X andY-coordinates of two points that are apart from each other in the X-axisdirection on the mark, whereby when carrying out processing feed of thechuck table in the imaging zone and carrying out imaging, the secondcamera is subjected to indexing feed based on the correction values orthe chuck table is rotated by the correction angle.

In the processing apparatus according to the second aspect of thepresent invention, the chuck table may preferably have a transparentmember that forms a holding surface configured to hold the workpiecethereon, the camera may preferably have the first camera and the secondcamera at positions which are up and down with the transparent memberinterposed therebetween, and the control unit may preferably furtherinclude a coordinate storage section configured to store in terms of Xand Y-coordinates a positional deviation between the first camerapositioned to image a predetermined region on the workpiece held on thechuck table and the second camera positioned to image the predeterminedregion, and is configured to correct the position of the second camerabased on the X and Y-coordinates stored in the coordinate storagesection such that the second camera can image the predetermined regionimaged by the first camera.

In the processing apparatus according to the second aspect of thepresent invention, the processing apparatus may preferably furtherinclude a display unit that displays a first image captured by the firstcamera and a second image captured by the second camera, and the controlunit may preferably further include an image control section configuredto display the first image and the second image in superposition orjuxtaposition on the display unit with one of the first image and thesecond image being inverted in the X-axis direction.

The present invention brings about an advantageous effect that areduction in processing accuracy can be suppressed while suppressing anincrease in cost.

The above and other objects, features and advantages of the presentinvention and the manner of realizing them will become more apparent,and the invention itself will best be understood from a study of thefollowing description and appended claims with reference to the attacheddrawings showing preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view depicting part of a processing apparatusaccording to a first embodiment;

FIG. 2 is a perspective view of a workpiece as an object to be processedby the processing apparatus depicted in FIG. 1;

FIG. 3 is a perspective view depicting a holding unit and a secondcamera in the processing apparatus depicted in FIG. 1;

FIG. 4 is a plan view schematically illustrating a processing zone andan imaging zone in the processing apparatus depicted in FIG. 1;

FIG. 5 is a view illustrating examples of a first image and a secondimage, which a display unit of the processing apparatus depicted in FIG.1 displays;

FIG. 6 is a view illustrating other examples of the first image and thesecond image, which the display unit of the processing apparatusdepicted in FIG. 1 displays;

FIG. 7 is a perspective view of the workpiece on which a cut groove isto be formed when a correction amount calculation section of theprocessing apparatus depicted in FIG. 1 calculates a correction amount;

FIG. 8 is a plan view schematically illustrating a state in which thecorrection amount calculation section of the processing apparatusdepicted in FIG. 1 is forming the cut groove in the workpiece depictedin FIG. 7;

FIG. 9 is a plan view schematically illustrating a state in which thecorrection amount calculation section of the processing apparatusdepicted in FIG. 1 has formed the cut groove in the workpiece depictedin FIG. 7;

FIG. 10 is a view illustrating a first image that a first camera of theprocessing apparatus depicted in FIG. 1 has captured by imaging one endportion of the cut groove;

FIG. 11 is a view illustrating another first image that the first cameraof the processing apparatus depicted in FIG. 1 has captured by imagingan opposite end portion of the cut groove;

FIG. 12 is a plan view schematically illustrating a state in which thecorrection amount calculation section of the processing apparatusdepicted in FIG. 1 is moving the workpiece with the cut groove formedtherein to the imaging zone;

FIG. 13 is a plan view, as seen from below, of the workpiece in theimaging zone as illustrated in FIG. 12;

FIG. 14 is a view illustrating a second image that a second camera ofthe processing apparatus depicted in FIG. 1 has captured by imaging theone end portion of the cut groove;

FIG. 15 is a view illustrating another second image that the secondcamera of the processing apparatus depicted in FIG. 1 has captured byimaging the opposite end portion of the cut groove;

FIG. 16 is a view illustrating a state in which the display unit of theprocessing apparatus depicted in FIG. 1 displays the first image and thesecond image in juxtaposition;

FIG. 17 is a view illustrating a state in which the display unit of theprocessing apparatus depicted in FIG. 1 displays the first image and thesecond image in superposition;

FIG. 18 is a perspective view depicting a configuration of part of aprocessing apparatus according to a second embodiment;

FIG. 19 is a perspective view depicting a holding unit and a secondcamera in the processing apparatus depicted in FIG. 18; and

FIG. 20 is a perspective view depicting the workpiece of FIG. 2 with atape bonded on a back surface thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the attached drawings, a description will be made indetail regarding embodiments of the present invention. However, thepresent invention shall not be limited by details that will be describedin the embodiments. Elements of configurations that will hereinafter bedescribed include those readily conceivable to persons skilled in theart and substantially the same ones. Further, the configurations thatwill hereinafter be described can be combined appropriately.Furthermore, various omissions, replacements, and modifications ofconfigurations can be made within the scope not departing from thespirit of the present invention.

First Embodiment

A processing apparatus according to a first embodiment of the presentinvention will be described based on the attached drawings, specificallyFIGS. 1 through 17. Reference will first be made to FIGS. 1 to 7. FIG. 1is a perspective view depicting part of the processing apparatusaccording to the first embodiment. FIG. 2 is a perspective view of aworkpiece as an object to be processed by the processing apparatusdepicted in FIG. 1. FIG. 3 is a perspective view depicting a holdingunit and a second camera in the processing apparatus depicted in FIG. 1.FIG. 4 is a plan view schematically illustrating a processing zone andan imaging zone in the processing apparatus depicted in FIG. 1. FIG. 5is a view illustrating examples of a first image and a second image,which a display unit of the processing apparatus depicted in FIG. 1displays. FIG. 6 is a view illustrating other examples of the firstimage and the second image, which the display unit of the processingapparatus depicted in FIG. 1 displays. FIG. 7 is a perspective view ofthe workpiece on which a cut groove is to be formed when a correctionamount calculation section of the processing apparatus depicted in FIG.1 calculates a correction amount.

The processing apparatus 1 according to the first embodiment is used tocut (equivalent to “process”) a workpiece 200 depicted in FIG. 2. Theworkpiece 200, as an object to be processed by the processing apparatus1 depicted in FIG. 1, is a wafer such as a disk-shaped semiconductorwafer or optical device wafer, which includes a substrate 201 formedwith silicon, sapphire, gallium arsenide, silicon carbide (SiC), or thelike. In the workpiece 200, devices 204 are formed in regions defined ina grid pattern on a front surface 202 of the substrate 201 by aplurality of streets 203.

The devices 204 are, for example, semiconductor devices such asintegrated circuits (ICs) or large scale integrations (LSIs), or imagesensors such as charge coupled devices (CCDs) or complementary metaloxide semiconductors (CMOSs). In the first embodiment, the workpiece 200includes a metal film 206 formed on a back surface 205 of the substrate201. The back surface 205 is located on a side opposite to the frontsurface 202. As the metal film 206 is formed on the back surface 205,the streets 203 cannot be detected even if the workpiece 200 is imagedby an infrared camera from the side of the back surface 205.

On the workpiece 200, key patterns 207 are formed corresponding to therespective devices 204. These key patterns 207 are used as detectiontargets at the time of alignment for positional registration between theworkpiece 200 and a cutting blade 21 of the processing apparatus 1. Asthe key patterns 207, characteristic portions of circuits in the devices204 are used, for example. In the first embodiment, the key patterns 207are each formed in a cruciform shape including two linear marks 208 and209 that intersect with each other and are parallel to the correspondingstreets 203. In the first embodiment, the workpiece 200 is bonded at thefront surface 202 thereof to a tape 211, to an outer peripheral edgeportion of which an annular frame 210 is attached, and is thereforesupported on the annular frame 210 with the metal film 206 on the sideof the back surface 205 being directed upward.

The processing apparatus 1 depicted in FIG. 1 is a cutting apparatus inwhich the workpiece 200 is held by a chuck table 12 of a holding unit 10and is cut along the streets 203 by the cutting blade 21, so that theworkpiece 200 is divided into the individual devices 204. As depicted inFIG. 1, the processing apparatus 1 includes the holding unit 10, acutting unit 20, a processing feed unit 30 that performs processing feedof the holding unit 10 in an X-axis direction (processing feeddirection) parallel to a horizontal direction, an indexing feed unit 40that performs indexing feed of the cutting unit 20 in a Y-axis direction(indexing feed direction) parallel to the horizontal direction andperpendicular to the X-axis direction, an undepicted cutting-in feedunit that performs cutting-in feed of the cutting unit 20 in a Z-axisdirection perpendicular to both the X-axis direction and the Y-axisdirection, a camera 50, and a control unit 100.

As depicted in FIGS. 1 and 3, the holding unit 10 has a housing 11 thatis moved in the X-axis direction by the processing feed unit 30, thechuck table 12 rotatably disposed on the housing 11, and a rotary driveunit 13 that rotates the chuck table 12 about its axis parallel to theZ-axis direction.

The chuck table 12 holds the workpiece 200 on a holding surface 124, andis rotatable about its axis parallel to the Z-axis. The chuck table 12is formed in a disc shape, and includes a frame 122 with a recessedportion 121 centrally formed in an upper surface thereof and adisc-shaped transparent member 123 fitted in the recessed portion 121 ofthe frame 122 and forming the holding surface 124.

The frame 122 is formed with a metal such as stainless steel, and isrotated by the rotary drive unit 13 about its axis parallel to theZ-axis direction. The transparent member 123 is formed from atransparent material such as quartz glass, borosilicate glass, sapphire,calcium fluoride, lithium fluoride, or magnesium fluoride, and has, asthe holding surface 124, an upper surface through which a number ofundepicted apertures opens. The workpiece 200 is mounted on the holdingsurface 124 via the tape 211, with the side of the front surface 202kept in contact with the holding surface 124.

The chuck table 12 includes a space formed in the recessed portion 121and connected to an undepicted vacuum suction source. When air is drawnthrough the space by the vacuum suction source, the workpiece 200mounted on the holding surface 124 is held under suction. In the firstembodiment, the chuck table 12 holds the workpiece 200 on the side ofthe front surface 202 under suction via the tape 211. It is to be notedthat, in the first embodiment, the tape 211 and the annular frame 210protrude to an outer peripheral side of the chuck table 12 when theworkpiece 200 is held under suction on the chuck table 12.

The rotary drive unit 13 serves to rotate the chuck table 12 about itsaxis parallel to the Z-axis direction. The rotary drive unit 13 rotatesthe chuck table 12 about its axis in a range greater than 180 degreesand smaller than 360 degrees. The rotary drive unit 13 is disposed onthe housing 11 that is subjected to processing feed in the X-axisdirection by the processing feed unit 30. The rotary drive unit 13includes a motor 131 fixed on a side wall of the housing 11, a pulley132 connected to an output shaft of the motor 131, and a belt 133wrapped on an outer periphery of the chuck table 12 and rotationallydriven by the pulley 132 about the axis of the chuck table 12. When themotor 131 for the rotary drive unit 13 is driven, the chuck table 12 isrotated about the axis thereof via the pulley 132 and the belt 133. Inthe first embodiment, the rotary drive unit 13 can rotate the chucktable 12, for example, 220 degrees both in one direction about the axisthereof and in an opposite direction that is a reverse direction to theone direction.

The cutting unit 20 is a processing unit that cuts, by the cutting blade21, the workpiece 200 held on the chuck table 12. Relative to theworkpiece 200 held on the chuck table 12, the cutting unit 20 isdisposed movably in the Y-axis direction by the indexing feed unit 40and is also disposed movably in the Z-axis direction by the undepictedcutting-in feed unit. The cutting unit 20 is disposed on a support frame(not depicted), which is disposed upright from an apparatus main body 2,by way of the indexing feed unit 40, the cutting-in feed unit, and thelike.

The cutting unit 20 can place the cutting blade 21 at a desired positionon the holding surface 124 of the chuck table 12 by the indexing feedunit 40 and the cutting-in feed unit. The cutting unit 20 includes thecutting blade 21, a spindle housing 22 disposed movably in the Y-axisdirection and the Z-axis direction by the indexing feed unit 40 and thecutting-in feed unit, and a spindle 23 arranged rotatably about its axison the spindle housing 22, driven by a motor (not depicted), andcarrying the cutting blade 21 mounted on a tip portion thereof.

The cutting blade 21 is an ultrathin cutting stone having asubstantially ring shape. In the first embodiment, the cutting blade 21is a what-is-called hub blade including a circular hub and an annularcutting edge. The annular cutting edge is disposed on an outerperipheral edge of the circular hub and is used to cut the workpiece200. The cutting edge is made from abrasive grains of diamond, cubicboron nitride (CBN), or the like and a bonding material (binder) such asa metal or a resin, and is formed with a predetermined thickness. It isto be noted that, in the present invention, the cutting blade 21 may bea what-is-called washer blade configured of only a cutting edge.

The spindle 23 rotates about its axis by the motor, thereby rotating thecutting blade 21 about its axis. It is to be noted that the axes of thecutting blade 21 and the spindle 23 in the cutting unit 20 are parallelto the Y-axis direction.

The processing feed unit 30 relatively moves the chuck table 12 and thecutting unit 20 in the X-axis direction, and in the first embodiment,moves the chuck table 12 in the X-axis direction. As appreciated fromthe foregoing, the term “processing feed” as used in this inventionmeans to move the chuck table 12 in the X-axis direction. As depicted inFIGS. 1 and 3, the processing feed unit 30 includes a known ball screw31 disposed rotatably about its axis, a known pulse motor 32 thatrotates the ball screw 31 about its axis, and known guide rails 33supporting the housing 11 movably in the X-axis direction. The ballscrew 31 and the guide rails 33 are parallel to the X-axis direction.

The processing feed unit 30 moves the holding unit 10 via the housing 11along the guide rails 33 between a processing zone (see FIG. 4) and animaging zone 5 (see FIG. 4). In the processing zone 3, the workpiece 200held on the chuck table 12 is cut by the cutting unit 20. In the imagingzone 5, the workpiece 200 is imaged by the camera 50 at a position thatis apart from the processing zone 3 by a predetermined distance 4 (seeFIG. 4) in the X-axis direction.

In the first embodiment, the processing zone 3 includes a position ofthe chuck table 12 (indicated by solid lines in FIG. 4) when theworkpiece 200 held on the chuck table 12 is cut by the cutting unit 20at one end thereof on a right side in the X-axis direction in FIG. 4,and a position of the chuck table 12 (indicated by dashed lines in FIG.4) when the workpiece 200 held on the chuck table 12 is cut by thecutting unit 20 at an opposite end thereof on a left side in the X-axisdirection in FIG. 4. The imaging zone 5 is apart from the processingzone 3 by the predetermined distance 4 rightward in FIG. 4. Further, theprocessing zone 3 is a guaranteed range in which the linear travelaccuracy of the chuck table 12 along the guide rails 33 has an accuracyneeded to divide the workpiece 200 into the individual devices 204,while the imaging zone 5 is a non-guaranteed range in which the lineartravel accuracy of the chuck table 12 along the guide rails 33 does nothave the accuracy needed to divide the workpiece 200 into the individualdevices 204. The term “the linear travel accuracy” of the chuck table 12along the guide rails 33 means an extent of a deviation of a movementtrajectory of the chuck table 12 along the guide rails 33 from theX-axis direction.

The indexing feed unit 40 relatively moves the chuck table 12 and thecutting unit 20 in the Y-axis direction, and in the first embodiment,moves the cutting unit 20 in the Y-axis direction. The cutting-in feedunit relatively moves the chuck table 12 and the cutting unit 20 in theZ-axis direction, and in the first embodiment, moves the cutting unit 20in the Z-axis direction. The indexing feed unit 40 and the cutting-infeed unit each include a known ball screw disposed rotatably about itsaxis, a known pulse motor that rotates the ball screw about its axis,and known guide rails supporting the cutting unit 20 movably in theY-axis direction or Z-axis direction.

The camera 50 images the workpiece 200 held on the chuck table 12, andis movable in the Y-axis direction. As depicted in FIG. 1, the camera 50has, at positions which are up and down with the transparent member 123interposed therebetween, a first camera 51 disposed in a vicinity of thecutting unit 20, and a second camera 52 that is more distant than thefirst camera 51 from the cutting unit 20.

The first camera 51 images the workpiece 200 held on the chuck table 12from above the holding surface 124. In the first embodiment, the firstcamera 51 is fixed on the spindle housing 22 of the cutting unit 20 suchthat the first camera 51 moves integrally with the cutting unit 20, andis disposed in the vicinity of the cutting unit 20. The first camera 51is fixed on the spindle housing 22 of the cutting unit 20, and thereforeis movable in the Y-axis direction by the indexing feed unit 40. In thefirst embodiment, the first camera 51 is arranged at a position wherethe center of its imaging area is located side by side with the cuttingblade 21 in the X-axis direction.

The first camera 51 includes an imaging element that images, from above,the workpiece 200 held on the holding unit 10 located in the processingzone 3 as the guaranteed range. Therefore, the first camera 51 isarranged in the guaranteed range. The imaging element is, for example, aCCD imaging element or a CMOS imaging element. The first camera 51images the workpiece 200 held on the chuck table 12 from above tocapture a first image 301 (see FIGS. 5 and 6), and outputs the firstimage 301 to the control unit 100.

The second camera 52 images the workpiece 200 held on the chuck table 12from below the holding surface 124 through the holding surface 124. Inthe first embodiment, the second camera 52 is arranged on a side fartherthan (on a right side of) the processing feed unit 30 in FIG. 1, and isarranged more distant than the first camera 51 from the cutting unit 20.Meanwhile, the second camera 52 is arranged on a movable plate 54 thatis moved in the Y-axis direction by a Y-axis moving unit 53 disposed onthe apparatus main body 2, and is therefore movable in the Y-axisdirection by the Y-axis moving unit 53. The second camera 52 is alsomovable in the Z-axis direction by a Z-axis moving unit 55 disposed onthe movable plate 54.

The Y-axis moving unit 53 and the Z-axis moving unit 55 each include aknown ball screw rotatably disposed about its axis, a known pulse motorthat rotates the ball screw about its axis, and known guide railsmovably supporting the movable plate 54 or the second camera 52 in theY-axis direction or the Z-axis direction.

The second camera 52 includes an imaging element that images, from belowthrough the transparent member 123, the workpiece 200 held on theholding unit 10 located in the imaging zone 5 as the non-guaranteedrange. Therefore, the second camera 52 is arranged in the non-guaranteedrange. The imaging element is, for example, a CCD imaging element or aCMOS imaging element. The second camera 52 images the workpiece 200 heldon the chuck table 12 from below through the transparent member 123 tocapture a second image 302 (see FIGS. 5 and 6), and outputs the secondimage 302 to the control unit 100. It is to be noted that, in the firstembodiment, the second image 302 is also used to perform an alignment.

The control unit 100 controls the above-described individual elements ofthe processing apparatus 1 independently or in combination to make theprocessing apparatus 1 perform a processing operation on the workpiece200. The control unit 100 is a computer including an arithmetic andlogic processing unit having a microprocessor such as a centralprocessing unit (CPU), a storage device having a memory such as a readonly memory (ROM) or a random access memory (RAM), and an input/outputinterface device. The arithmetic and logic processing unit of thecontrol unit 100 performs arithmetic and/or logic processing inaccordance with a computer program stored in the storage device, andoutputs control signals for the processing apparatus 1 to theabove-described elements of the processing apparatus 1 via theinput/output interface device.

Further, the processing apparatus 1 is connected to a display unit 110and an input unit (not depicted). The display unit 110 includes a liquidcrystal display device or the like that is connected to the control unit100 and displays status of processing operations, images, and so on. Theinput unit is connected to the control unit 100, and is used when anoperator records information regarding processing details and the like.In the first embodiment, the input unit includes at least one of a touchpanel incorporated in the display unit 110 or an external input devicesuch as a keyboard.

The display unit 110 displays the first image 301 captured by the firstcamera 51 and the second image 302 captured by the second camera 52. Thecontrol unit 100 receives an operation from the operator via the inputunit, and generates control signals pursuant to the operation from theoperator. Based on the control signals, the display unit 110 displaysthe first image 301 and the second image 302 in juxtaposition in theX-axis direction as illustrated in FIG. 5 or in superposition asillustrated in FIG. 6.

When displaying the first image 301 and the second image 302, thedisplay unit 110 displays them with one of the first image 301 and thesecond image 302 being inverted in the X-axis direction. The expression“with one of the first image 301 and the second image 302 being invertedin the X-axis direction” means that both the first image 301 and thesecond image 302 are displayed as images captured by imaging theworkpiece 200 held on the chuck table 12 from above, or that both thefirst image 301 and the second image 302 are displayed as imagescaptured by imaging the workpiece 200 held on the chuck table 12 frombelow. In the first embodiment, the display unit 110 displays on adisplay screen such that both the first image 301 and the second image302 are displayed as images captured by imaging the workpiece 200 heldon the chuck table 12 from above. In the first embodiment, the displayunit 110 can display the first and second images 301 and 302 both injuxtaposition in the X-axis direction and in superposition. In thepresent invention, however, it is sufficient if at least one of thesedisplay modes is feasible.

The processing apparatus 1 also includes an X-axis direction positiondetection unit for detecting the position of the chuck table 12 in theX-axis direction, a Y-axis direction position detection unit fordetecting the position of the cutting unit 20 in the Y-axis direction, aZ-axis direction position detection unit for detecting the position ofthe cutting unit 20 in the Z-axis direction, and an angle detection unitfor detecting the rotation angle of the cutting unit 20 about its axis.The X-axis direction position detection unit and the Y-axis directionposition detection unit can each include a linear scale parallel to theX-axis direction or the Y-axis direction, and a reading head that isdisposed movably in the X-axis direction or the Y-axis direction by theprocessing feed unit 30 or the indexing feed unit 40 and readsgradations of the linear scale. The Z-axis direction position detectionunit can detect the position of the cutting unit 20 in the Z-axisdirection by counting the number of pulses of the pulse motor thatrotates the associated ball screw about its axis. The processingapparatus 1 also includes a second Y-axis direction position detectionunit for detecting the position of the second camera 52 in the Y-axisdirection. Each detection unit outputs detection results to the controlunit 100.

The detection unit 100 also includes a correction amount calculationsection 101, a coordinate calculation section 102, a coordinate storagesection 103, an image control section 104, and an imaging area controlsection 105. The correction amount calculation section 101 forms a cutgroove 400 (see FIGS. 4, 8, and 9) as a linear processed mark in theworkpiece 200 (hereinafter designated by numeral 200-1), which isdepicted in FIG. 7 and is held under suction on the chuck table 12, bythe cutting unit 20 while moving the chuck table 12 from the processingzone 3 toward the imaging zone 5 in the X-axis direction. The coordinatecalculation section 102 detects the cut groove 400 from the first image301 and the second image 302, and calculates X-coordinates andY-coordinates of a center 401 of the cut groove 400. The coordinatestorage section 103 stores the X-coordinates and Y-coordinates of thecenter 401 of the cut groove 400 in the first and second images 301 and302 as calculated by the coordinate calculation section 102.

In the first embodiment, the workpiece 200-1 depicted in FIG. 7 is awhat-is-called dummy wafer formed of the substrate 201 alone, whichincludes neither the devices 204 formed on the front surface 202 nor themetal film 206 formed on the back surface 205. In the workpiece 200-1,portions identical to those of the workpiece 200 as the object to beprocessed by the processing apparatus 1 are identified by the samenumerals, and their description will be omitted herein. Similar to theworkpiece 200 as the object to be processed by the processing apparatus1, the workpiece 200-1 is bonded at the front surface 202 thereof to thetape 211, to the outer peripheral edge portion of which the annularframe 210 is attached and is therefore supported on the annular frame10, so that the workpiece 200-1 is held under suction on the chuck table12. The cut groove 400 extends through the substrate 201 of theworkpiece 200-1 from the back surface 205 to the front surface 202, andis formed linearly along the X-axis direction because the processingzone 3 is the guaranteed range.

The coordinate calculation section 102 extracts the cut groove 400 fromthe first and second images 301 and 302 captured through imaging by thefirst and second cameras 51 and 52. The coordinate calculation section102 calculates, from the detection results of the X-axis directionposition detection unit and the Y-axis direction position detectionunit, the X coordinate in the X-axis direction and the Y coordinate inthe Y-axis direction of the center 401 of the cut groove 400 in thefirst image 301. In addition, the coordinate calculation section 102also calculates, from the detection results of the X-axis directionposition detection unit and the second Y-axis direction positiondetection unit, the X coordinate in the X-axis direction and the Ycoordinate in the Y-axis direction of the center 401 of the cut groove400 in the second image 302. It is to be noted that, in the firstembodiment, the coordinate calculation section 102 presents an Xcoordinate in terms of a distance in the X-axis direction from apredetermined reference position on the holding surface 124, andpresents a Y coordinate in terms of a distance in the Y-axis directionfrom the predetermined reference position the holding surface 124.

Because the imaging zone 5 falls in the non-guaranteed range, the cutgroove 400 extracted from the second image 302 and indicated by a solidline in FIG. 13, as viewed in plan, is tilted with respect to the cutgroove 400 extracted from the first image 301 and indicated by a dashedline in FIG. 13. Therefore, each position of the cut groove 400 in thefirst image 301 captured by the first camera 51 and the correspondingposition of the cut groove 400 in the second image 302 captured by thesecond camera 52 deviate from each other in the X-axis direction and inthe Y-axis direction.

The correction amount calculation section 101, the coordinatecalculation section 102, the coordinate storage section 103, and theimage control section 104 perform a correction amount calculationoperation to calculate correction amounts for a deviation between eachposition of the cut groove 400 in the first image 301 captured by thefirst camera 51 and the corresponding position of the cut groove 400 inthe second image 302 captured by the second camera 52, thereby enablingthe first camera 51 and the second camera 52 to image the same positionon the workpiece 200 held on the chuck table 12. This correction amountcalculation operation is performed at the time of shipment of theprocessing apparatus 1 from a factory and also at periodic timings (forexample, every year) after its shipment from the factory.

Next, a description will be made of the correction amount calculationoperation while describing the individual elements of the control unit100. FIG. 8 is a plan view schematically illustrating a state in whichthe correction amount calculation section of the processing apparatusdepicted in FIG. 1 is forming the cut groove in the workpiece depictedin FIG. 7. FIG. 9 is a plan view schematically illustrating a state inwhich the correction amount calculation section of the processingapparatus depicted in FIG. 1 has formed the cut groove in the workpiecedepicted in FIG. 7. FIG. 10 is a view illustrating a first image thatthe first camera of the processing apparatus depicted in FIG. 1 hascaptured by imaging one end portion of the cut groove. FIG. 11 is a viewillustrating another first image that the first camera of the processingapparatus depicted in FIG. 1 has captured by imaging an opposite endportion of the cut groove. FIG. 12 is a plan view schematicallyillustrating a state in which the correction amount calculation sectionof the processing apparatus depicted in FIG. 1 is moving the workpiecewith the cut groove formed therein to the imaging zone. FIG. 13 is aplan view as seen from below of the workpiece in the imaging zoneillustrated in FIG. 12. FIG. 14 is a view illustrating a second imagethat the second camera of the processing apparatus depicted in FIG. 1has captured by imaging the one end portion of the cut groove. FIG. 15is a view illustrating another second image that the second camera ofthe processing apparatus depicted in FIG. 1 has captured by imaging theopposite end portion of the cut groove. FIG. 16 is a view illustrating astate in which the display unit of the processing apparatus depicted inFIG. 1 displays the first image and the second image in juxtaposition.FIG. 17 is a view illustrating a state in which the display unit of theprocessing apparatus depicted in FIG. 1 displays the first image and thesecond image in superposition.

In the correction amount calculation operation, the operator mounts theworkpiece 200 on the holding surface 124 of the chuck table 12 in theholding unit 10 via the tape 211. When the control unit 100 subsequentlyreceives a start instruction from the operator, the processing apparatus1 starts a correction amount calculation operation.

In the correction amount calculation operation, the control unit 100rotates the cutting blade 21 of the cutting unit 20, and holds theworkpiece 200 under suction on the holding surface 124 of the chucktable 12 of the holding unit 10 via the tape 211. While moving the chucktable 12, which is indicated by the solid lines in FIG. 8, from theprocessing zone 3 to the imaging zone 5 via a position where the chucktable 12 is indicated by the dashed lines, the correction amountcalculation section 101 causes the cutting blade 21 to cut into theworkpiece 200 until the cutting blade 21 reaches the tape 211. Thecorrection amount calculation section 101 forms the cut groove 400 inthe workpiece 200-1 as illustrated in FIGS. 8 and 9, and then causes thefirst camera 51 to image predetermined positions on opposite endportions 402 and 403 of the cut groove 400.

Described specifically, after the formation of the cut groove 400illustrated in FIG. 9, the first camera 51 images the one end portion402 of the cut groove 400 to capture a first image 301 (hereinafterdesignated by numeral 301-2) illustrated in FIG. 10, and also images theopposite end portion 403 of the cut groove 400 to capture another firstimage 301 (hereinafter designated by numeral 301-3) illustrated in FIG.11. The correction amount calculation section 101 acquires the firstimage 301-2 and the first image 301-3.

The coordinate calculation section 102 calculates the X coordinate (X1)and Y coordinate (Y1) of the center 401 of the cut groove 400 in thefirst image 301-2, and the coordinate storage section 103 stores thecoordinates (X1, Y1) of the center 401 of the cut groove 400 in thefirst image 301-2. The coordinate calculation section 102 calculates theX coordinate (X2) and Y coordinate (Y1) of the center 401 of the cutgroove 400 in the first image 301-3, and the coordinate storage section103 stores the coordinates (X2, Y1) of the center 401 of the cut groove400 in the first image 301-3. In this manner, the coordinate calculationsection 102 calculates the coordinates (X1, Y1) of the center 401 of theone end portion 402 of the cut groove 400 in the processing zone 3 andthe coordinates (X2, Y1) of the center 401 of the opposite end portion403 of the cut groove 400 in the processing zone 3, and the coordinatestorage section 103 stores the coordinates (X1, Y1) and the coordinates(X2, Y1).

When the chuck table 12 is moved as mentioned above, the chuck table 12approaches the imaging zone 5 as illustrated by the dashed lines in FIG.8. After the chuck table 12 has approached the imaging zone 5 asindicated by the dashed lines in FIG. 12, the correction amountcalculation section 101 moves the chuck table 12 further toward theimaging region 5, and then causes the second camera 52 to image thepredetermined positions (the same positions as the imaging positions bythe first camera 51) on the opposite end portions 402 and 403 (see FIG.13) of the cut groove 400. Described specifically, the second camera 52images the one end portion 402 of the cut groove 400 to capture a secondimage 302 (hereinafter designated by numeral 302-2) illustrated in FIG.14, and also images the opposite end portion 403 of the cut groove 400to capture another second image 302 (hereinafter designated by numeral302-3) illustrated in FIG. 15. The correction amount calculation section101 acquires the second image 302-2 and the second image 302-3.

The coordinate calculation section 102 calculates the X coordinate (X1)and Y coordinate (Y2) of the center 401 of the cut groove 400 in thesecond image 302-2, and the coordinate storage section 103 stores thecoordinates (X1, Y2) of the center 401 of the cut groove 400 in thesecond image 302-2. The coordinate calculation section 102 calculatesthe X coordinate (X2) and Y coordinate (Y3) of the center 401 of the cutgroove 400 in the second image 302-3, and the coordinate storage section103 stores the coordinates (X2, Y3) of the center 401 of the cut groove400 in the second image 302-3. In this manner, the coordinatecalculation section 102 calculates the coordinates (X1, Y2) of thecenter 401 of the one end portion 402 of the cut groove 400 in theimaging zone 5 and the coordinates (X2, Y3) of the center 401 of theopposite end portion 403 of the cut groove 400 in the imaging zone 5,and the coordinate storage section 103 stores the coordinates (X1, Y2)and the coordinates (X2, Y3).

From the above-mentioned coordinates (X1, Y1), (X2, Y1), (X1, Y2), and(X2, Y3), the correction amount calculation section 101 calculates anangle θ formed by the cut groove 400 extracted from the second image 302and indicated by the solid line in FIG. 13 and the cut groove 400extracted from the first image 301 and indicated by the dashed line inFIG. 13. Specifically, the angle θ is calculated by the followingformula 1.

θ=tan⁻¹{(Y3−Y2)/(X2−X1)}  Formula 1

The correction amount calculation section 101 stores the angle θ, whichhas been calculated by the formula 1, as a correction value, i.e., acorrection angle for the chuck table 12 in the coordinate storagesection 103.

In addition, the correction amount calculation section 102 alsocalculates, from the above-mentioned coordinates (X1, Y1), (X2, Y1),(X1, Y2), and (X2, Y3), a difference between the Y coordinates of thesame position (the position of the same X coordinate) on the holdingsurface 124 in the processing zone 3 and the imaging zone 5.Specifically, at the position of the coordinate (X1), the differencebetween the Y coordinates is calculated to be (Y2−Y1), and at theposition of the coordinate (X2), the difference between the Ycoordinates is calculated to be (Y3−Y1). The difference of the Ycoordinates at the respective positions between the coordinate (X1) andthe coordinate (X2) is then calculated using the above-mentioneddifference (Y2−Y1) of the Y coordinates, the above-mentioned difference(Y3−Y1) of the Y coordinates and the above-mentioned angle θ.

The correction amount calculation section 101 stores, as correctionvalues in the Y-axis direction in the imaging zone 5, theabove-mentioned difference (Y2−Y1) of the Y-coordinates, theabove-mentioned difference (Y3−Y1) of the Y coordinates, and thedifference of the Y coordinates at the respective positions between thecoordinate (X1) and the coordinate (X2), in the coordinate storagesection 103. In short, taking into consideration a phenomenon that adeviation of a second predetermined value (mm) occurs in the Y-axisdirection if processing feed is performed over a first predeterminedvalue (mm) in the X-axis direction, the correction amount calculationsection 101 calculates the correction values in the Y-axis direction inthe imaging zone 5 and stores them in the coordinate storage section103.

As described above, the correction amount calculation section 101calculates the correction values in the Y-axis direction and thecorrection angle for the chuck table 12, both, in the imaging zone 5from the Y coordinates (Y1), (Y2), (Y3), etc. of the centers 401 of bothof the end portions 402 and 403 of the single cut groove 400, thecenters 401 being two points that are apart from each other in theX-axis direction on the cut groove 400 and stores them in the coordinatestorage section 103. In the first embodiment, the correction amountcalculation section 101 calculates both the correction values in theY-axis direction and the correction angle for the chuck table 12 andstores them in the coordinate storage section 103. In the presentinvention, however, it is sufficient to calculate and store at leasteither the correction values or the correction angle.

The coordinate storage section 103 positions the second camera 52 belowboth of the end portions 402 and 403 of the cut groove 400, the endportions 402 and 403 being the regions imaged by the first camera 51,and causes the second camera 52 to image the end portions 402 and 403,and stores the difference (Y2−Y1) of the Y coordinates at the coordinate(X1), the difference (Y3−Y1) of the Y coordinates at the coordinate(X2), and the difference of the Y coordinates at the respectivepositions between the coordinate (X1) and the coordinate (X2), thedifferences having been calculated by the correction amount calculationsection 101, so that the positional deviation between the imaging areaof the first camera 51 and the imaging area of the second camera 52 isstored as X coordinates and Y coordinates. As appreciated from theforegoing, the difference (Y2−Y1) of the Y coordinates at the coordinate(X1), the difference (Y3−Y1) of the Y coordinates at the coordinate(X2), and the difference of the Y coordinates at the respectivepositions between the coordinate (X1) and the coordinate (X2) indicate,as X coordinates and Y coordinates, the positional deviation between theimaging area of the first camera 51 and the imaging area of the secondcamera 52.

In the correction amount calculation operation, the image controlsection 104 receives the operation from the operator via the input unit,outputs to the display unit 110 control signals pursuant to theoperation from the operator, and displays the first image 301 and thesecond image 302 in juxtaposition in the X-axis direction on the displayunit 110 as illustrated in FIG. 16 or displays the first image 301 andthe second image 302 in superposition on the display unit 110 asillustrated in FIG. 17. It is to be noted that FIGS. 16 and 17 presentexamples of the display of the first and second images 301-3 and 302-3of the opposite end portion 403 by the display unit 110. The correctionamount control operation ends when the coordinate storage section 103stores the correction values in the Y-axis direction and the correctionangle for the chuck table 12.

To enable the second camera 52 to image the same position on theworkpiece 200 as the first camera 51 based on the correction values inthe Y-axis direction as stored in the coordinate storage section 103when moving the chuck table 12 in the X-axis direction in the imagingzone 5 to perform an alignment by imaging the workpiece 200 held on thechuck table 12 with the second camera 52 in the processing operation bythe processing apparatus 1, the imaging area control section 105controls the Y-axis moving unit 53 to correct the position of the secondcamera 52 in the Y-axis direction. As an alternative, when moving thechuck table 12 in the X-axis direction in the imaging zone 5 to performan alignment, the imaging area control section 105 controls the rotarydrive unit 13 based on the correction angle for the chuck table 12 asstored in the coordinate storage section 103 to rotate the chuck table12 about its axis according to the correction angle such that the secondcamera 52 can image the same position on the workpiece 200 as the firstcamera 51.

Specifically, the imaging area control section 105, when moving thechuck table 12 in the X-axis direction in the imaging zone 5 to performan alignment, controls the Y-axis moving unit 53 by the storedcorrection values in the Y-axis direction to move the second camera 52downward in FIG. 12 if the correction values in the Y-axis direction asstored in the coordinate storage section 103 indicate that the sameposition on the workpiece 200 is located on a more upper side in FIG. 12in the imaging zone 5 than in the processing zone 3. Similarly, theimaging area control section 105 moves the second camera 52 upward bythe stored correction values in the Y-axis direction in FIG. 12 if thecorrection values in the Y-axis direction as stored in the coordinatestorage section 103 at the time of the alignment indicate that the sameposition on the workpiece 200 is located on a more lower side in FIG. 12in the imaging zone 5 than in the processing zone 3.

Further, the imaging area control section 105, when moving the chucktable 12 in the X-axis direction in the imaging zone 5 to perform analignment, controls the rotary drive unit 13 to rotate the chuck table12 in a direction of an arrow 502 of FIG. 12 by the stored correctionangle if the correction angle for the chuck table 12 as stored in thecoordinate storage section 103 indicates that the same position on theworkpiece 200 deviates more in a direction of the arrow 501 of FIG. 12in the imaging zone 5 than in the processing zone 3. Similarly, theimaging area control section 105 rotates the chuck table 12 by thestored correction angle in the direction of the arrow 501 of FIG. 12 ifthe correction angle for the chuck table 12 as stored in the coordinatestorage section 103 at the time of the alignment indicates that the sameposition on the workpiece 200 deviates more in the direction of thearrow 502 of FIG. 12 in the imaging zone 5 than in the processing zone3.

In the processing operation by the processing apparatus 1, the cutgroove 400 is imaged from above by the first camera 51, the cut groove400 is imaged from below by the second camera 52, and a kerf check isthen performed to determine whether or not a deviation of the cut groove400, which has been formed in the workpiece 200, from a desired positionand sizes or the like of chippings occurred on both edges of the cutgroove 400 are within predetermined tolerances. Here, the imaging areacontrol section 105 also corrects the position of the second camera 52in the Y-axis direction. It is to be noted that a kerf check isconducted at a predetermined timing such as every time a predeterminednumber of cut grooves 400 has been formed or every time a predeterminednumber of workpieces 200 has been cut.

When performing the kerf check, the imaging area control section 105uses, as a positional deviation between the imaging area of the firstcamera 51 and the imaging area of the second camera 52, the difference(Y2−Y1) of the Y coordinates at the coordinate (X1), the difference(Y3−Y1) of the Y coordinates at the coordinate (X2), and the differenceof the Y coordinates at the respective positions between the coordinate(X1) and the coordinate (X2), all of which are stored in the coordinatestorage section 103, and controls the Y-axis moving unit 53 to correctthe position of the second camera 52 in the Y-axis direction such thatthe second camera 52 can image the same position on the workpiece 200 asthe first camera 51.

Specifically, the imaging area control section 105, after imaging theworkpiece 200 by the first camera 51 to perform the kerf check, controlsthe Y-axis moving unit 53 by the stored correction values in the Y-axisdirection to move the second camera 52 downward in FIG. 12 and thenimages the workpiece 200 by the second camera 52 if the correctionvalues in the Y-axis direction as stored in the coordinate storagesection 103 indicate that the same position on the workpiece 200 islocated on a more upper side in FIG. 12 in the imaging zone 5 than inthe processing zone 3. Similarly, the imaging area control section 105,after imaging the workpiece 200 by the first camera 51 at the time ofthe kerf check, moves the second camera 52 upward by the storedcorrection values in the Y-axis direction in FIG. 12 and then images theworkpiece 200 by the second camera 52 if the correction values in theY-axis direction as stored in the coordinate storage section 103indicate that the same position on the workpiece 200 is located on amore lower side in FIG. 12 in the imaging zone 5 than in the processingzone 3.

The respective functions of the correction amount calculation section101, the coordinate calculation section 102, the image control section104, and the image area control section 105 are realized throughexecution of computer programs, which are stored in the storage deviceof the control unit 100, by the arithmetic and logic processing unit.The function of the coordinate storage section 103 is realized by thestorage device of the control unit 100.

Next, a description will be made regarding a processing operation by theprocessing apparatus 1. In the processing operation, the operator firstrecords information regarding processing details in the control unit100, and mounts the workpiece 200 on the holding surface 124 of thechuck table 12 of the holding unit 10 via the tape 211 prior to cuttingprocessing. Subsequently, the processing apparatus 1 starts theprocessing operation when the control unit 100 receives a startinstruction for the processing operation from the operator.

In the processing operation, the processing apparatus 1 controls theindividual elements of the control unit 100, and after the workpiece 200is held under suction on the holding surface 124 of the chuck table 12via the tape 211, the cutting blade 21 of the cutting unit 20 isrotated, the chuck table 12 is moved to the imaging zone 5, and thechuck table 12 is stopped in the imaging zone 5. Based on the correctionvalues in the Y-axis direction and the correction angle for the chucktable 12, which the imaging area control section 105 has stored in thecoordinate storage section 103, the processing apparatus 1 adjusts theposition of the second camera 52 in the Y-axis direction and thedirection of the chuck table 12 about its axis based on the correctionvalues in the Y-axis direction and the correction angle for the chucktable 12 as stored by the imaging area control section 105 in thecoordinate storage section 103.

In the processing operation, the processing apparatus 1 further controlsthe individual elements of the control unit 100, and the workpiece 200on the chuck table 12 is imaged from below by the second camera 52 andan alignment is performed to conduct positional registration between theworkpiece 200 and the cutting blade 21. In the processing operation,with the check table 12 and the cutting blade 21 of the cutting unit 20being relatively moved along a desired one of the streets 203, thecutting blade 21 is caused to cut into the workpiece 200 along thedesired street 203 until the tape 211 is reached. The cutting unit 20cuts, along the desired street 203, the workpiece 200 held on the chucktable 12, so that a cut groove is formed in the workpiece 200 along thedesired street 203.

In the processing operation, the processing apparatus 1 also performs akerf check at a predetermined timing. In the processing operation, theprocessing apparatus 1 ends the processing operation when the workpiece200 has been cut along all the streets 203.

The above-described processing apparatus 1 according to the firstembodiment includes the correction amount calculation section 101 thatcalculates the correction values in the Y-axis direction and thecorrection angle for the chuck table 12, both, in the imaging zone 5from the coordinates (X1, Y1) and (X2, Y1) of the center 401 of the cutgroove 400 as calculated from the first images 301-2 and 301-3 acquiredby imaging both of the end portions 402 and 403 of the cut groove 400 bythe first camera 51 and the coordinates (X1, Y2) and (X2, Y3) of thecenter 401 of the cut groove 400 as calculated from the second images302-2 and 302-3 acquired by imaging both of the end portions 402 and 403of the cut groove 400 by the second camera 52.

The processing apparatus 1 also includes the imaging area controlsection 105 that, when performing an alignment, moves the second camera52 in the Y-axis direction and rotates the chuck table 12 about its axisbased on the correction values in the Y-axis direction and thecorrection angle for the chuck table 12 as calculated by the correctionamount calculation section 101 such that the first camera 51 and thesecond camera 52 image the same position on the workpiece 200.

When performing the alignment by imaging the workpiece 200 held on thechuck table 12 by the second camera 52 arranged in the non-guaranteedrange, the processing apparatus 1 positions the second camera 52 suchthat the first camera 51 and the second camera 52 image the sameposition on the workpiece 200 held on the chuck table 12. The processingapparatus 1 can therefore perform the alignment accurately, therebyenabling to suppress processing at a wrong position in the processingoperation.

Even if the workpiece 200 held on the chuck table 12 is imaged by thesecond camera 52 arranged in the non-guaranteed range, the processingapparatus 1 can also accurately perform an alignment, and therefore cansuppress the need for costly guide rails or longer guide rails whichwould otherwise be required for the performance of an accuratealignment.

As a consequence, the processing apparatus 1 brings about anadvantageous effect that a reduction in processing accuracy can besuppressed while suppressing an increase in cost.

Using the X coordinates and Y coordinates of the positional deviationbetween the imaging area of the first camera 51 and the imaging area ofthe second camera 52 as stored in the coordinate storage section 103, inother words, the difference (Y2−Y1) of the Y coordinates at thecoordinate (X1), the difference (Y3−Y1) of the Y coordinates at thecoordinate (X2), and the difference of the Y coordinates at therespective positions between the coordinate (X1) and the coordinate (X2)when performing the kerf check, the processing apparatus 1 also controlsthe Y-axis moving unit 53 to correct the position of the second camera52 in the Y-axis direction such that the second camera 52 can image thesame position on the workpiece 200 as the first camera 51.

When performing the kerf check, the processing apparatus 1 can thereforeimage the same position on the workpiece 200 by the first camera 51arranged in the guaranteed range and the second camera 52 arranged inthe non-guaranteed range. Accordingly, the processing apparatus 1 canaccurately perform the kerf check from both above and below of theworkpiece 200, and can suppress wrong determination as to processingresults in the processing operation.

As a consequence, the processing apparatus 1 can bring about anadvantageous effect that a kerf check can be precisely performed whilesuppressing an increase in cost.

Second Embodiment

A processing apparatus according to a second embodiment of the presentinvention will be described based on the attached drawings, specificallyFIGS. 18 to 20. Reference will first be made to FIGS. 18 and 19. FIG. 18is a perspective view depicting a configuration of part of theprocessing apparatus according to the second embodiment. FIG. 19 is aperspective view depicting a holding unit and a second camera in theprocessing apparatus depicted in FIG. 18. In FIGS. 18 and 19, portionsidentical to those in the first embodiment are identified by the samenumerals, and their description will be omitted herein.

A processing apparatus 1-2 according to the second embodiment is thesame as the processing apparatus 1 of the first embodiment except that alinear mark 61 is formed in the holding surface 124 of the chuck table12 and that, in a correction amount calculation operation, thecorrection amount calculation section 101 images the mark 61 by thefirst camera 51 and the second camera 52 and calculates correctionvalues in the Y-axis direction, a positional deviation between theimaging area of the first camera 51 and the imaging area of the secondcamera 52, and a correction angle for the chuck table 12, and thecoordinate storage section 103 stores a positional deviation between thefirst camera 51 and the second camera 52 as calculated by the correctionamount calculation section 101.

In the second embodiment, as depicted in FIGS. 18 and 19, a second mark62 that crosses the linear mark 61 at right angles and overlaps the mark61 is formed in the holding surface 124 of the chuck table 12 inaddition to the mark 61, so that a mark 63 composed of the marks 61 and62 is formed.

In the correction amount calculation operation, the control unit 100holds the workpiece 200 under suction on the holding surface 124 of thechuck table 12 of the holding unit 10 via the tape 211 without rotatingthe cutting blade 21 of the cutting unit 20, and positions the chucktable 12 in the processing zone 3 to make the mark 61 and the firstcamera 51 face each other in the Z-axis direction. In the correctionamount calculation operation, the correction amount calculation section101 images the linear mark 61 in the chuck table 12 by the first camera51, and rotates the chuck table 12 to adjust a longitudinal direction ofthe mark 61 to a direction parallel to the X-axis direction.

In the correction amount calculation operation, the correction amountcalculation section 101 causes the first camera 51 to imagepredetermined positions on opposite end portions of the mark 61 whilemoving the chuck table 12 along the X-axis direction from the processingzone 3 to the imaging zone 5, thereby acquiring a first image 301(hereinafter designated by numeral 301-4) captured by imaging one endportion of the mark 61 with the first camera 51 and another first image301 (hereinafter designated by numeral 301-5) captured by imaging anopposite end portion of the mark 61 with the first camera 51.

The coordinate calculation section 102 extracts the mark 61 from thefirst image 301-4 and calculates the X coordinate (X1) and the Ycoordinate (Y1) of a center of the mark 61, and the coordinate storagesection 103 stores the coordinates (X1, Y1) of the center of the mark 61in the first image 301-4. The coordinate calculation section 102extracts the mark 61 from the first image 301-5 and calculates the Xcoordinate (X2) and the Y coordinate (Y1) of the center of the mark 61,and the coordinate storage section 103 stores the coordinates (X2, Y1)of the center of the mark 61 in the first image 301-5. In this manner,the coordinate calculation section 102 calculates the coordinates (X1,Y1) of the center of the one end portion of the mark 61 and thecoordinates (X2, Y1) of the center of the opposite end portion of themark 61, both, in the processing zone 3, and stores the coordinates (X1,Y1) and the coordinates (X2, Y1) in the coordinate storage section 103.

After the chuck table 12 has approached the imaging zone 5, thecorrection amount calculation section 101 moves the chuck table 12further in the imaging zone 5, and causes the second camera 52 to imagethe predetermined positions (the same positions as the imaging positionsof the first camera 51) on both the end portions of the mark 61. Thecorrection amount calculation section 101 acquires a second image 302(hereinafter designated by numeral 302-4) captured by imaging the oneend portion of the mark 61 with the second camera 52 and another secondimage 302 (hereinafter designated by numeral 302-5) captured by imagingthe opposite end portion of the mark 61 with the second camera 52.

The coordinate calculation section 102 extracts the mark 61 from thesecond image 302-4 and calculates the X coordinate (X1) and Y coordinate(Y2) of the center of the mark 61, and the coordinate storage section103 stores the coordinates (X1, Y2) of the center of the mark 61 in thesecond image 302-4. The coordinate calculation section 102 extracts themark 61 from the second image 302-5 and calculates the X coordinate (X2)and Y coordinate (Y3) of the center of the mark 61, and the coordinatestorage section 103 stores the coordinates (X2, Y3) of the center of themark 61 in the second image 302-5. In this manner, the coordinatecalculation section 102 calculates the coordinates (X1, Y2) of thecenter of the one end portion of the mark 61 and the coordinates (X2,Y3) of the center of the opposite end portion of the mark 61, both, inthe imaging zone 5, and the coordinate storage section 103 stores thecoordinates (X1, Y2) and the coordinates (X2, Y3).

From the above-mentioned coordinates (X1, Y1), (X2, Y1), (X1, Y2), and(X2, Y3), the correction amount calculation section 101 calculates anangle θ formed by the mark 61 extracted from the second image 302 andthe mark 61 extracted from the first image 301 by the formula 1 as inthe first embodiment, and stores the calculated angle θ as a correctionvalue, i.e., a correction angle for the chuck table 12 in the coordinatestorage section 103.

In addition, the correction amount calculation section 101 alsocalculates, from the above-mentioned coordinates (X1, Y1), (X2, Y1),(X1, Y2), and (X2, Y3), a difference of the Y coordinates for therespective X coordinates of the same position on the holding surface 124in the processing zone 3 and the imaging zone 5 as in the firstembodiment.

The correction amount calculation section 101 stores, as correctionvalues in the Y-axis direction in the imaging zone 5, the difference(Y2−Y1) of the Y-coordinates, the difference (Y3−Y1) of the Ycoordinates, and the difference of the Y coordinates at the respectivepositions between the coordinate (X1) and the coordinate (X2), whichhave been calculated as in the first embodiment, in the coordinatestorage section 103.

As described above, the correction amount calculation section 101calculates the correction values in the Y-axis direction and thecorrection angle for the chuck table 12, both, in the imaging zone 5from the Y coordinates (Y1), (Y2), (Y3), etc. of the centers of both ofthe end portions of the single mark 61, the centers being two pointsthat are apart from each other in the X-axis direction, and stores themin the coordinate storage section 103. In the second embodiment, thecorrection amount calculation section 101 calculates both the correctionvalues in the Y-axis direction and the correction angle for the chucktable 12 and stores them in the coordinate storage section 103. In thepresent invention, however, it is sufficient to calculate and store atleast either the correction values or the correction angle as in thefirst embodiment.

The coordinate storage section 103 positions the second camera 52 belowboth of the end portions of the mark 61, the end portions being theregions imaged by the first camera 51, and causes the second camera 52to image the end portions, and stores the difference (Y2−Y1) of the Ycoordinates at the coordinate (X1), the difference (Y3−Y1) of the Ycoordinates at the coordinate (X2), and the difference of the Ycoordinates at the respective positions between the coordinate (X1) andthe coordinate (X2), the differences having been calculated by thecorrection amount calculation section 101, so that the positionaldeviation between the imaging area of the first camera 51 and theimaging area of the second camera 52 is stored as X coordinates and Ycoordinates.

After the correction amount calculation section 101 has calculated thecorrection values in the Y-axis direction, the correction angle for thechuck table 12, and the positional deviation between the imaging area ofthe first camera 51 and the imaging area of the second camera 52, all,in the imaging zone 5, and the coordinate storage section 103 has storedthem, the processing apparatus 1-2 according to the second embodimentoperates as in the first embodiment.

The correction amount calculation section 101 calculates the correctionvalues in the Y-axis direction, the correction angle for the chuck table12, and the positional deviation between the imaging area of the firstcamera 51 and the imaging area of the second camera 52, all, in theimaging zone 5, the coordinate storage section 103 stores them, and thenthe processing apparatus 1-2 operates as in the first embodiment.Therefore, the above-described processing apparatus 1-2 according to thesecond embodiment, like the first embodiment, can bring about theadvantageous effect that a reduction in processing accuracy can besuppressed while suppressing an increase in cost.

Reference will next be made to FIG. 20. FIG. 20 is a perspective viewdepicting the workpiece of FIG. 2 with the tape bonded on the backsurface thereof. In FIG. 20, portions identical to those in the firstembodiment are identified by the same numerals, and their descriptionwill be omitted herein.

If the tape 211 is bonded to the side of the back surface 205 of theworkpiece 200 and the devices 204 are directed upward, as depicted inFIG. 20, in the second embodiment, the processing apparatus 1-2 may holdthe workpiece 200 under suction on the holding surface 124 of the chucktable 12 via the tape 211. If this is the case, the first camera 51 andthe second camera 52 may image, for example, both end portions of one ofthe marks 208 and 209 in a desired one of the key patterns 207,specifically the mark 208, the correction amount calculation section 101may calculate the correction values in the Y-axis direction, thecorrection angle for the chuck table 12, and the positional deviationbetween the imaging area of the first camera 51 and the imaging area ofthe second camera 52, all, in the imaging zone 5, the coordinate storagesection 103 may store them, and then the processing apparatus 1-2 mayoperate as in the first embodiment.

After imaging the cut groove 400, the mark 61, or the mark 208 by thefirst camera 51 and the second camera 52 and calculating the correctionvalues in the Y-axis direction, the correction angle for the chuck table12, and the positional deviation between the imaging area of the firstcamera 51 and the imaging area of the second camera 52, all, in theimaging zone 5, the present invention may rotate the chuck table 12 90degrees about its axis, and may then confirm whether the cut groove 400,the mark 61, or the mark 208 extends along the Y-axis direction.Described specifically, the correction amount calculation section 101images the cut groove 400, the mark 61, or the mark 208 by the firstcamera 51 and the second camera 52 and calculates the correction valuesin the Y-axis direction, the correction angle for the chuck table 12,and the positional deviation between the imaging area of the firstcamera 51 and the imaging area of the second camera 52, all, in theimaging zone 5, rotates the chuck table 12 90 degrees about its axis,and then confirms whether the cut groove 400, the mark 61, or the mark208 extends along the Y-axis direction. In the case of the secondembodiment, it is desired to confirm whether the mark 62 or 209 extendsin the X-axis direction.

The present invention shall not be limited to the above-describedembodiments. In other words, the present invention can be practiced withvarious modifications within the scope not departing from the spirit ofthe present invention. In the embodiments, the processing apparatuses 1and 1-2 are cutting apparatuses that cut the workpieces 200 and 200-1.In the present invention, however, the processing apparatus is notlimited to such a cutting apparatus, but may be, for example, a laserprocessing apparatus that irradiates a laser beam of a wavelength havingabsorption in or transmission through the workpieces 200 and 200-1. Ifthe processing apparatus 1 or 1-2 is a laser processing apparatus, itslaser beam irradiation unit that irradiates a laser beam corresponds tothe processing unit, and a laser-processed groove or a modified layerformed in the workpiece 200 or 200-1 corresponds to a processed mark. Inthe present invention, the first camera 51 and second camera 52 may beinfrared cameras.

The present invention is not limited to the details of theabove-described preferred embodiment. The scope of the invention isdefined by the appended claims and all changes and modifications as fallwithin the equivalence of the scope of the claims are therefore to beembraced by the invention.

What is claimed is:
 1. A processing apparatus comprising: a holding unithaving a rotatable chuck table configured to hold a workpiece; aprocessing unit configured to process the workpiece held on the chucktable; a processing feed unit that carries out processing feed of theholding unit in an X-axis direction; an indexing feed unit that carriesout indexing feed of the processing unit in a Y-axis direction; a camerathat images the workpiece held on the chuck table and is movable in anindexing feed direction; and a control unit configured to control theholding unit, the processing unit, the processing feed unit, theindexing feed unit, and the camera, wherein the processing feed unitincludes guide rails, and is configured to move the holding unit alongthe guide rails between a processing zone, in which the workpiece isprocessed by the processing unit, and an imaging zone, in which theworkpiece is imaged by the camera at a position that is apart from theprocessing zone by a predetermined distance in the X-axis direction, andthe control unit includes a correction amount calculation sectionconfigured such that, after forming a linear processed mark in theworkpiece by the processing unit while carrying out processing feed ofthe chuck table, the chuck table is moved to the imaging zone, theprocessed mark is imaged by the camera, and correction values in theY-axis direction or a correction angle for the chuck table are or isthen calculated from Y-coordinates of two points that are apart fromeach other in a processing feed direction on the processed mark, wherebywhen carrying out processing feed of the chuck table in the imagingzone, the camera is corrected in position in the Y-axis direction basedon the correction values or the chuck table is rotated by the correctionangle.
 2. The processing apparatus according to claim 1, wherein thechuck table has a transparent member that forms a holding surfaceconfigured to hold the workpiece thereon, the camera has, at positionswhich are up and down with the transparent member interposedtherebetween, a first camera in a vicinity of the processing unit and asecond camera that is more distant than the first camera from theprocessing unit, and the control unit further includes a coordinatestorage section configured to store in terms of X and Y-coordinates apositional deviation between the first camera positioned to image apredetermined region on the workpiece held on the chuck table and thesecond camera positioned to image the predetermined region, and isconfigured to correct the position of the second camera based on the Xand Y-coordinates stored in the coordinate storage section such that thesecond camera can image the predetermined region imaged by the firstcamera.
 3. The processing apparatus according to claim 2, furthercomprising: a display unit that displays a first image captured by thefirst camera and a second image captured by the second camera, whereinthe control unit further includes an image control section configured todisplay the first image and the second image in superposition orjuxtaposition on the display unit with one of the first image and thesecond image being inverted in the processing feed direction.
 4. Aprocessing apparatus comprising: a holding unit having a rotatable chucktable configured to hold a workpiece; a processing unit configured toprocess the workpiece held on the chuck table; a processing feed unitthat carries out processing feed of the holding unit in an X-axisdirection; an indexing feed unit that carries out indexing feed of theprocessing unit in a Y-axis direction; a camera that images theworkpiece held on the chuck table and is movable in the Y-axisdirection; and a control unit configured to control the holding unit,the processing unit, the processing feed unit, the indexing feed unit,and the camera, wherein the processing feed unit includes guide rails,and is configured to move the holding unit along the guide rails betweena processing zone, in which the workpiece is processed by the processingunit, and an imaging zone, in which the workpiece is imaged by thecamera at a position that is apart from the processing zone by apredetermined distance, the camera has a first camera in a vicinity ofthe processing unit, and a second camera that is more distant than thefirst camera from the processing unit, and the control unit includes acorrection amount calculation section configured to image a linear markin the workpiece or the chuck table by the first camera, to rotate thechuck table to adjust the mark to a direction parallel to the X-axisdirection, to move the chuck table to the imaging zone to image the markby the second camera, and then to calculate correction values in theY-axis direction or a correction angle for the chuck table from X andY-coordinates of two points that are apart from each other in the X-axisdirection on the mark, whereby when carrying out processing feed of thechuck table in the imaging zone and carrying out imaging, the secondcamera is subjected to indexing feed based on the correction values orthe chuck table is rotated by the correction angle.
 5. The processingapparatus according to claim 4, wherein the chuck table has atransparent member that forms a holding surface configured to hold theworkpiece thereon, the camera has the first camera and the second cameraat positions which are up and down with the transparent memberinterposed therebetween, and the control unit further includes acoordinate storage section configured to store in terms of X andY-coordinates a positional deviation between the first camera positionedto image a predetermined region on the workpiece held on the chuck tableand the second camera positioned to image the predetermined region, andis configured to correct the position of the second camera based on theX and Y-coordinates stored in the coordinate storage section such thatthe second camera can image the predetermined region imaged by the firstcamera.
 6. The processing apparatus according to claim 5, furthercomprising: a display unit that displays a first image captured by thefirst camera and a second image captured by the second camera, whereinthe control unit further includes an image control section configured todisplay the first image and the second image in superposition orjuxtaposition on the display unit with one of the first image and thesecond image being inverted in the X-axis direction.